The present invention relates to an airbag device having an inflator which generates gas for inflating and deploying an airbag. More particularly, the invention relates to a device having an inflator of a type that a combustion chamber and a filter chamber are separately provided.
Regardless of the type of airbags (e.g. driver airbags, front-passenger airbags, side impact airbags, and curtain airbags), conventional pyrotechnic inflators generally fall into the following two types: a type wherein the propellant and a filter are housed in one chamber (for example, a one-chamber type as disclosed in WO9908907); and a type where these components are housed in respective separate chambers (for example, a two-chamber type as disclosed in DE29819168U1). That is, the one-chamber type inflator has one chamber in which propellant and a filter are housed. The two-chamber type inflator comprises a combustion chamber in which propellant is filled, a filter chamber in which a filter is housed, and a partition provided between the combustion chamber and the filter chamber wherein the partition is formed with a hole for allowing the communication between the combustion chamber and the filter chamber from the initiation of combustion until the combustion pressure reaches the maximum value. The combustion gas starts to flow into the filter chamber at the initiation of combustion. This inflow of gas causes a little delay to rise the combustion pressure to the maximum value. Further, the delay slows the speed of combustion.
It is desired to shorten the starting timing of rising the inner pressure of an airbag and to shorten the time period required from the start of rising of the inner pressure until the inner pressure reaches the maximum value, for improving the initial restraining capability of an airbag device.
It is desired to provide an inflator which has an increased degree of freedom of design for positioning a gas port.
It is desired to provide an inflator which provides for an increased degree of freedom of design for easily changing its profile to be suitable for any housing space.
In order to solve the above-described problems, an inflator of the present invention comprises: a propellant, an igniter for igniting the propellant, a combustion chamber in which the propellant is burned, a filter chamber in which a filter is accommodated, a partition separating the combustion chamber and the filter chamber, communication orifices formed in the partition for allowing the communication between the combustion chamber and the filter chamber, and gas ports for supplying inflating gas into an airbag, and further comprising a closing mechanism which provides for an air tight closure at the communication orifices until the inner pressure of the combustion chamber reaches a predetermined pressure.
According to this structure, the combustion chamber is closed so that the pressure in the combustion chamber rises quickly. The closing mechanism releases when the pressure reaches the predetermined pressure, thereby reducing the delay in the start of rising the inner pressure of an airbag, shortening the time period required from the start of rising of the inner pressure until the inner pressure reaches the maximum value, and thus improving the initial restraining capability of an airbag device.
The inflator of the present invention is characterized in that the closing mechanism breakable members which can be broken at the predetermined pressure. According to this structure, inexpensive breakable members such as aluminum film can be employed as the closing mechanism or means.
The inflator of the present invention is further characterized in that the predetermined pressure is slightly lower than the maximum combustion pressure of the propellant in the combustion chamber. According to this structure, the reliability of releasing action of the closing mechanism can be improved because the action is not affected by variation in the maximum combustion pressure due to individual differences of the propellant.
The inflator of the present invention is characterized in that the predetermined pressure is a value around the lower limit of a variation range of the maximum combustion pressure. According to this structure, the reliability of releasing action of the closing mechanism can be improved because the action is not affected by variation in the maximum combustion pressure due to individual differences of the propellant.
An airbag device according to the present invention may include: a propellant, an igniter for igniting the propellant, a combustion chamber in which the propellant is burned, a filter chamber in which a filter is accommodated, a partition separating the combustion chamber and the filter chamber, communication orifices formed in the partition for allowing communication between the combustion chamber and the filter chamber, and gas ports for supplying inflating gas into an airbag, and is characterized in that the gas ports can be formed at any places in the outer periphery of the inflator, except a portion adjacent to the combustion chamber.
According to this structure, the gas ports may be formed in almost all outer periphery adjacent to the filter chamber, thus increasing the degree of freedom of design for positioning gas ports. In addition, the filter can be used as heat-absorbing mechanism through its entire surface, thus improving the endothermic effect of the filter.
An airbag device of the present invention is characterized by comprising an airbag connected to the aforementioned inflator. According to this structure, an airbag device can be obtained which has excellent rising characteristics of the inner pressure of the airbag.
The airbag device of the present invention is characterized in that the airbag has a gas inlet facing to the gas ports of the aforementioned inflator. According to this structure, the gas inlet of the airbag is disposed to face to the gas ports so as to cope with multidirectional or bidirectional gas spouted out simultaneously from the gas ports of the inflator of this type, thereby effectively introducing the inflating gas of the inflator of this type into the airbag. This structure can speed up the initial deployment of the airbag or can deploy multiple areas of airbags at once.
In an alternative embodiment, an inflator of the present invention may comprise: a propellant, an igniter for igniting the propellant, a combustion chamber in which the propellant is burned, a filter chamber in which a filter is positioned, a partition separating the combustion chamber and the filter chamber, communication orifices formed in the partition for allowing the communication between the combustion chamber and the filter chamber, and gas ports for supplying inflating gas into an airbag, and wherein the combustion chamber and the filter chamber are arranged in parallel in the longitudinal direction with the partition being interposed therebetween.
According to this structure, the inflator can be made to be short in the longitudinal direction and thin in the thickness so that the inflator can be suitably used in such a case to be housed in a limited space such as an A-pillar, a B-pillar, a C-pillar, and a space behind a garnish. By arranging the combustion chamber and the filter chamber to be offset in parallel or making the filter chamber longer than the combustion chamber in the longitudinal direction, the projecting portion of the filter chamber can be effectively used as a connecting portion with the airbag. Ends of the projecting portion can be provided with gas ports.
An airbag device of the present invention is characterized by comprising an airbag which can be connected to the connecting portion of the aforementioned inflator. According to this structure, a curtain airbag device or a side impact airbag device can be obtained which has excellent rising characteristics of the inner pressure of the airbag.
In another alternative embodiment, the inflator of the present invention is characterized in that the filter chamber has projecting portions on both ends thereof in the longitudinal direction so that the filter chamber is longer than the combustion chamber, and further has connecting portions formed on the ends of the projecting portions which can be connected to the airbag. According to this structure, since gas can be supplied to the airbag through gas ports facing in directions opposite to each other, the deployment of the airbag can be started at two locations at the same time, thus speeding up the deployment of the airbag. It is effective for deploying an airbag having a wide areas such as a curtain airbag. An airbag device of the present invention may include an airbag which can be connected to the connecting portions of the aforementioned inflator.
According to this structure, a curtain airbag device can be obtained which has excellent rising characteristics of the inner pressure of the airbag. Since gas spouted out in the opposite directions can be effectively introduced into the airbag at the same time i.e. bidirectional gas can be supplied simultaneously into the airbag, the gas can quickly fill the entire airbag, thus speeding up the deployment of the airbag.
In yet another alternative embodiment, the inflator of the present invention is characterized in that the filter chamber and the combustion chamber are arranged to be offset from each other in the longitudinal direction with the partition being interposed therebetween so that the filter chamber and the combustion chamber project in the opposite directions to each other, and further has a connecting portion formed on the end of the projecting portion of the filter chamber. According to this structure, when this inflator is used for a curtain airbag, for example, the inflator has advantages that it can be made shorter than a conventional inflator and that the projecting portion can be used as a connecting portion with the airbag. It is especially advantageous in a case that the inflator is connected to the curtain airbag around the A-pillar, the B-pillar, or the C-pillar.
An airbag device of the present invention includes an airbag which can be connected to the connecting portion of the aforementioned inflator. According to this structure, a curtain airbag device can be obtained which has excellent rising characteristics of the inner pressure of the airbag and of which inflator can be housed in a long curved limited space such as a A-pillar and a C-pillar.
In an alternative embodiment, an inflator of the present invention may comprise: a propellant, an igniter for igniting the propellant, a combustion chamber in which the propellant is burned, a filter chamber in which a filter is positioned, a partition separating the combustion chamber and the filter chamber, communication orifices formed in the partition for allowing communication between the combustion chamber and the filter chamber, and gas ports for supplying inflating gas into an airbag, and is characterized in that the filter is substantially formed in a thick disk-like configuration wherein one surface of the filter is arranged adjacent to the combustion chamber via the partition.
According to this structure, since the gas ports can be formed in the top surface in addition to the side surface of the inflator, the airbag can be controlled to be deployed in a desired condition (for instance, a front portion of the airbag is deployed prior to the other portion). It is especially advantageous in a case that the inflator is used for a driver airbag. An airbag device of the present invention may include an airbag connected to the aforementioned inflator. According to this structure, a driver airbag device can be obtained which has excellent rising characteristics of the inner pressure of the airbag. Since the gas ports can be formed in the top surface in addition to the side surface of the inflator, a driver airbag device can be obtained in which a front portion of the airbag can be initially deployed by gas spouted out through the gas ports of the top surface so that it is suitable for early restraint.
In yet another alternative embodiment, an inflator of the present invention may comprise: a propellant, an igniter for igniting the propellant, a combustion chamber in which the propellant is burned, a filter chamber in which a filter is positioned, a partition separating the combustion chamber and the filter chamber, communication orifices formed in the partition for allowing the communication between the combustion chamber and the filter chamber, and gas ports for supplying inflating gas into an airbag, and is characterized in that the filter is substantially formed in a hollow cylindrical configuration and the combustion chamber is formed in the hollow portion of the filter via the partition.
According to this structure, this inflator can be employed as an inflator for a front passenger airbag. Therefore, an inflator for a front passenger airbag can be obtained which can provide excellent rising characteristics of inner pressure of the airbag. In case that the inflator is used for a front passenger airbag, the gas ports can be positioned at any places in a wide side surface and portions of ends of the cylindrical portion, thereby increasing the degree of freedom of design for positioning gas ports.
An airbag device of the present invention may include an airbag connected to the aforementioned inflator.
According to this structure, a front passenger airbag device can be obtained which has excellent rising characteristics of the inner pressure of the airbag. The airbag device is suitable for a curtain airbag, a side impact airbag, a front-passenger airbag, or a driver airbag, of which profile is compact, which has an increased degree of freedom of design for positioning a gas port and setting the flow of gas.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.